@tld - Any other js error on the page could result in breaking this functionality ( as it would be in most cases where js related code breaks ). Check your browser console log and see if there are any js errors on the page. If there are no js errors then this should work seamlessly. Also you might want to check your server error logs to see if it picks up something.
@companyjuice - Same for you, check your browser console log and see if it shows any js errors.
Check this link for more details on how to do that -> https://developers.google.com/chrome-developer-tools/docs/console#opening_the_console